1. Field of the Invention
This invention relates to a method of sulfating or sulfonating liquid organic materials.
2. Description of the Prior Art
The sulfonation or sulfation of organic compounds has been carried out in gas-liquid contact processes that use horizontally disposed reaction zones inside which the liquid is made to flow in a turbulent annular path, driven by a gaseous mixture of sulfur dioxide and an inert gas. Also, gas-liquid hydrobromination reactions have been carried out in a process which calls for contact between gaseous hydrogen bromide and a thin turbulent film of the liquid reactant. The film, in this prior process, can be a rising annular film, a concurrent or countercurrent falling film, a horizontally propelled film or the like.
Of these prior gas-liquid reactions that involve concurrent annular flow of the vertical or horizontal type all have been heretofore carried out in cylindrical reaction vessels of relatively small cross section. This is particularly true of the above-mentioned sulfation which is carried out in horizontal tubes of about 5 mm. diameter
Use of small diameter reaction zones has limited the capacity of the reaction vessel, has increased its cost, and has complicated its maintenance. Moreover, while representing improvements over other gas-liquid reaction methods, these small diameter reaction zones are limited in the completeness of reaction and quality of reacted product they can achieve as evidenced by charring or the formation of colored by-product impurities. These latter limitations in the case of the sulfonation or sulfation are believed by the applicants to be caused by the unevenness of the reaction in the smaller sized tubes, caused in turn by non-uniform flow. Applicants have found in this reaction that, generally speaking, the greater the velocity the better is the degree of completion of the reaction. In horizontally disposed reaction zones the bias of the flow owing to gravity must be overcome by the use of small diameter reaction zones coupled with turbulence to achieve annular (called "turbannular") flow. This factor of bias of gravity must be balanced by a maximum gas flow rate above which the flow of the liquid ceases to be uniform.
In a sulfonation or sulfation reaction the recovery of unreacted materials and their reuse are very difficult, and also the removal from the reaction product of colored by-product impurities (decoloration) is difficult and uneconomical. Therefore, it is required to increase the degree of completion of reaction and prevent the formation of colored by-product impurities as much as possible.